English version

Proposal's abstract

The present project represents a fundamental research about the propagation of waves and pulses in inhomogeneous media, with possible extentions toward policrystallyne magnetic media where the inhomogenities appear due to the non-uniformity of the magnetic field in the sample. In the case of non-magnetic inhomogeneous media the study of periodic inhomogenities can be of great interest. In this case there might be some interesting applications in the domain of acoustic and ultraacoustic structures which could be used to reduce the noise pollution.

Objectives

O1 – The development of numerical methods and the application of these methods in the case of wave propagation in inhomogeneous media.

O2 – Experimental studies on the evaluation of elastic constants for homogenous and inhomogeneous media by using natural frequnecy and transfer power measurements

O3 – The development of some software programs and computer simulations of the wave propagation in inhomogeneous media

O4 – The application of the studies in the case of media which presents periodic inhomogenities

O5 – The extension of the formalism of wave propagation in inhomogeneous media for the evaluation of elastic constants variation due to the magnetic field in the case of feromagnetic probes

O6 – The study of the behavior of feromagnetic probes in alternate magnetic fields, magnetoacoustic effect measurements

O7 – The study of the correlation between the magnetoacoustic behavior of feromagnetic probes and the structure of the magnetic domains.

Stages

Stage 1 (October 26, 2006 - December 5, 2006)

For the Coordinating Team:

a) The theoretical study of the models and computational formalism regarding the wave propagation phenomena in non-magnetic elastic media which presents some inhomogenities and the evaluation of various physical quantities which can be measured and can give us informations about the elastic constants of the material: the analyse of the eigenfrequencies, dispersion and the power transmission coefficient (Activities I.1, I.2). These actions will be described in the Scientific Report.

b) The development of a experimental setup able to determination by means of non-contact methods (laser interferometry with Doppler effect + signal preamplifiers + data acquisition+ experimental data analysis) the eigenfrequencies and the acoustic and ultraacoustic power transmission coefficients for non-magnetic homogenous samples or media which presents periodic inhomogenities of the cross section. The elastic constants will be estimated. Also we will analyse the influence of the mechanical stress on the elastic behaviour of the considered samples. The experimental results will be presented as measurements reports and will be discussed by the members of the team (Activities 1.3,1.4,1.5).

c) The management activity during the first stage (Activity I.6)

For Partner 1

The partner doesn't have any activity in this stage.

Stage 2 (December 6, 2006 - December 15, 2007)

For the Coordinating Team:

a) The development of some software programs designed toward the simulation of the propagation of waves in media with periodic inhomogenities, which can be of interest in the manufacturing of some structures designed to reduce the noise pollution. The testing of these programs and the correlation of them with experimental data.

b) The extension of the study toward magnetic elastic media (steel and nickel ferromagnetic bars) starting from the idea that a non-uniform internal field can induce an inhomogenity of the elastic constants, inhomogenity which can be described by means of magnetostriction measurements (Activities II.2, II.3). The evaluation of some dependencies between the magnetostriction constant and the Young modulus of ferromagnetic bars.

c) The correlation between the magnetization processes and the magnetostriction, the evaluation of the elastic constant modifications of the ferromagnetic sample by means of computer simulations and experimental measurements of the elastic constant. Magnetostriction measurements in collaboration with CNRS Grenoble.The correlation between the magnetization processes and the magnetoacoustic effect measurements.

d) Magnetoacoustic measurements.Correlation between the magnetization process and magnetoacoustic results. The influence of the internal defects or defect clusters on the shape of the line of magnetoacoustic effect. (Activities II.5,II.6)

e) The management of the project, second stge.(Activity  II.7)

For Partner 1

a) Metallographic measurements on non-stressed samples or samples which were previously involved in mechanical deformations and acoustic measurements.Interpretation of the experimental data and their forwarding to the coordinating team as analysis bulletins (Activity II.1).

b) Visualisation and estimation of the shape of magnetic domains and domain walls by using the magnetic force microscopy. Observations connected with the domain and domain wall dynamics on ferromagnetic steal and nickel probes (Activity II.1)

c)  Partner’s management activity during second stge(Activity II.7)

For the Coordinating Team: The elaboration of the Final Scientific Report.